.box1 {
  width: 50px;
  height: 50px;
  background-color: pink;
}
.box2 {
  width: 10px;
  height: 10px;
  border: 1px solid;
}
.box {
  width: 200px;
  height: 300px;
}
.box {
  height: false;
  width: 200px;
}
.box {
  width: 1px;
  height: 0px;
}
.box {
  width: 100px;
  height: 10px;
  border: 20px;
}
.box2 {
  width: 100px;
  height: 100px;
}
.box3 {
  width: 30px;
}
.box4 {
  width: -10px;
}
.box5 {
  width: 100px;
}
/*除法需要加小括号  */
.box6 {
  width: 10px;
}
.box2 {
  background-image: "./imgs/dog.png";
}
